g. michael blackburn*, jacqueline cherfils, gerard p. moss ... · chemistry, biophysics, chemistry,...

Pure Appl Chem 2017 89(5) 653ndash675

IUPAC Recommendations

G Michael Blackburn Jacqueline Cherfils Gerard P Moss Nigel G J Richards Jonathan P Waltho Nicholas H Williams and Alfred Wittinghofer

How to name atoms in phosphates polyphosphates their derivatives and mimics and transition state analogues for enzyme-catalysed phosphoryl transfer reactions (IUPAC Recommendations 2016)DOI 101515pac-2016-0202Received February 4 2016 accepted January 12 2017

Abstract Procedures are proposed for the naming of individual atoms P O F N and S in phosphate esters amidates thiophosphates polyphosphates their mimics and analogues of transition states for enzyme-catalyzed phosphoryl transfer reactions Their purpose is to enable scientists in very different fields eg bio-chemistry biophysics chemistry computational chemistry crystallography and molecular biology to share standard protocols for the labelling of individual atoms in complex molecules This will facilitate clear and unambiguous descriptions of structural results as well as scientific intercommunication concerning them At the present time perusal of the Protein Data Bank (PDB) and other sources shows that there is a limited degree of commonality in nomenclature but a large measure of irregularity in more complex structures The recommendations described here adhere to established practice as closely as possible in particular to IUPAC and IUBMB recommendations and to ldquobest practicerdquo in the PDB especially to its atom labelling of amino acids and particularly to Cahn-Ingold-Prelog rules for stereochemical nomenclature They are designed to work in complex enzyme sites for binding phosphates but also to have utility for non-enzymatic systems Above all the recommendations are designed to be easy to comprehend and user-friendly

Keywords atom names for transition states naming phosphate transition states P O F and N atom labels phosphate analogues phosphate atom labels phosphate nomenclature phosphate stereochemical naming phosphoryl transfer polyphosphates recommendations

CONTENTS1 INTRODUCTION 6542 EXISTING RECOMMENDATIONS 655

Article note This manuscript (PAC-REC-16-02-02) was prepared in the framework of IUPAC project 2013-039-2-300

Corresponding authors G Michael Blackburn Department of Molecular Biology Krebs Institute University of Sheffield S10 2TN UK e-mail gmblackburnsheffieldacuk and Gerard P Moss Queen Mary University of London School of Biological and Chemical Sciences London E1 4NS UK e-mail gpmossqmulacukJacqueline Cherfils Laboratoire de Biologie et Pharmacologie Appliqueacutee CNRS ndash Eacutecole Normale Supeacuterieure Paris-Saclay Cachan France httporcidorg0000-0002-8966-3067Nigel G J Richards Department of Chemistry Indiana University Purdue University Indianapolis IL 46202 USA and School of Chemistry Cardiff University Cardiff CF10 3AT UKJonathan P Waltho Biosciences Institute University of Manchester M1 7DN UK httporcidorg0000-0002-7402-5492Nicholas H Williams Chemistry Department University of Sheffield Sheffield S3 7HF UKAlfred Wittinghofer Group for Structural Biology Max-Planck-Institut fuumlr Molekulare Physiologie 44227 Dortmund Deutschland

copy 2017 IUPAC amp De Gruyter This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 40 International License For more information please visit httpcreativecommonsorglicensesby-nc-nd40Brought to you by | Cardiff University

AuthenticatedDownload Date | 6717 1153 AM

654emspenspenspenspthinspemspG M Blackburn et al How to name atoms in phosphates polyphosphates

3 RECOMMENDATIONS FOR LABELLING PHOSPHORUS ATOMS IN PHOSPHATES 6564 RECOMMENDATIONS FOR LABELLING OXYGEN ATOMS IN PHOSPHATES 6595 RECOMMENDATIONS FOR LABELLING FLUORINE AND OTHER ATOMS IN

PHOSPHATE TRANSITION STATE ANALOGUES 6646 RECOMMENDATIONS FOR LABELLING VANADATE AND TUNGSTATE ANALOGUES

OF PHOSPHATES 6687 SUMMARY 671 APPENDIX ndash A GUIDE FOR THE USE OF CAHN-INGOLD-PRELOG RULES FOR PROCHIRALITY 672 MEMBERSHIP OF THE SPONSORING BODY 674 REFERENCES 674

1 IntroductionThe advent of stereochemical studies on phosphate esters and diesters with particular reference to their enzyme catalysed reactions initially through the work of Knowles [1] and of Lowe [2] placed new demands on the nomenclature of the oxygen atoms of the transferring phosphoryl group PO3

thinspminus1 In early work employ-ing thiophosphates made chiral by the specific introduction of oxygen-18 paired with oxygen-16 the direct application of Cahn-Ingold-Prelog (CIP) Rules for prochirality [3 4] resolved the problem by labelling the oxygen atoms (Rp) and (Sp) as appropriate [5ndash7] The more advanced use of 16O 17O and 18O bonded to the same phosphorus [8] led to the concept of pro-pro-pro-chirality at phosphorus which was still capable of CIP identification [2 8] However such isotopic labelling is experimentally demanding and not necessarily appli-cable to stereochemical problems now more readily amenable to analysis through advances in protein crys-tallography The increasing frequency of binary and tertiary structures of proteins in complex with phosphate ester substrates andor analogues has enabled a rapidly expanding number of enzyme catalysed reactions to be investigated by structural and computational methods [9ndash11] Indeed there are now over 1600 ligands in the PDB having a phosphoryl group component These are associated with over 28 000 deposited structures While many of these structures can be and have been labelled for their phosphorus and phosphoryl oxygen atoms through current practice comparative studies of related structures easily identify multiple inconsist-encies in labelling that arise from variable methods of naming N O and P atoms

This situation has become increasingly complex as a result of the introduction and development of metal fluoride (MFx) analogues of the PO3

thinspminus group in studies on transition state analogues (TSA) for phosphoryl transfer enzymes Trifluoroberyllate (BeF3

thinspminus)2 is a ground state analogue for phosphate with characteristic tetrahedral geometry when ligated to anionic oxygen Tetrafluoroaluminate (AlF4

thinspminus)3 is a mimic for concerted phosphoryl transfer in multiple enzymes though it has octahedral geometry Aluminium trifluoride (AlF3)4 forms trigonal bipyramidal (tbp) TSA complexes that have the correct 3-D geometry for concerted PO3

thinspminus group transfer but lack its anionic charge These two values converge in the relatively smaller number of trifluoro-magnesate complexes (MgF3

thinspminus)5 which are both anionic and have tbp geometry Indeed some of the AlF3 com-plexes have been shown in reality to be MgF3

thinspminus complexes in solution [12ndash14] The growth in use of these four types of MFx complexes is illustrated in Fig 1 In addition there are many significant structures of phosphoryl transfer enzyme complexes that include vanadium(V) or tungsten(VI) complexes either as tetrahedral phos-phate mimics or as tbp mimics of transition states The relative growth in use of these six species is presented in Fig 1 The double change from four coordinate tetrahedral PO4 to five coordinate tbp OndashMF3ndashO and six

1enspThe description of the trigonal planar monoanionic PO3 species as a phosphoryl group is in line with long-established usage in biochemistry biomolecular chemistry and molecular biology We note that the IUPAC recommendation is that the species lsquophosphoryl grouprsquo relates to the neutral diatomic trivalent species equivPO2enspBeF3

thinspminus PDB ligand name Beryllium trifluoride ion PDB code BEF IUPAC name Trifluoridoberyllate3enspAlF4

thinspminus PDB ligand code ALF IUPAC name Tetrafluoridoaluminate4enspAlF3 PDB and IUPAC name Aluminum fluoride PDB ligand code AF35enspMgF3

thinspminus PDB ligand code MGF IUPAC name Trifluoridomagnesate

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Download Date | 6717 1153 AM

G M Blackburn et al How to name atoms in phosphates polyphosphatesemspthinspenspenspenspemsp655

coordinate octahedral OndashMF4ndashO complexes adds a new dimension to the problem of the atomic description of these complexes The need to solve this general problem provided the principal motivation for the develop-ment of these standardized naming conventions

As the development of our protocols progressed it became apparent to us that a rational logical set of labels for the 5- and 6-coordinate systems described above could only be established on the basis of a clear definition of the systematic labelling of phosphorus atoms in standard multiple phosphate molecules that already extends to eight in the case of hexaphosphoinositol bisphosphates [15] It needed to be followed by a comprehensive system for oxygen atom labelling to include both bridge and non-bridge atoms in linear chains of phosphates as for the 13 oxygen atoms of 5prime-adenosyl 5primePrime-guanosyl P1 P4-tetraphosphate [16] and the 3 non-isotopically identifiable oxygen atoms of the PO3

thinspminus group of terminal phosphates With those objec-tives accomplished our recommendations could then be developed to incorporate both the fluorine ligands of MFx systems and the oxygen atoms of vanadate and tungstate analogues of phosphates and their TSAs

The basic strategy of the recommendations is built on the recognition that a phosphate monoester com-prises an alkoxy group and a phosphoryl group (ROHthinsp+thinspPO3

thinspminus) a monoalkyl diphosphate comprises a phosphate monoester and a second phosphoryl group (ROPO3

thinspminusthinsp+thinspPO3thinspminus) a monoalkyl triphosphate comprises a monoalkyl

diphosphate and a third phosphoryl group and so on For simplicity we have ignored anionic charges on phosphoryl oxygen atoms and we have treated P=O ldquodouble bondsrdquo as PndashO single bonds because there is no π-bonding in the phosphoryl group While we do not seek to claim that our coverage has been exhaustive we believe that the principles for naming atoms set out here will prove generally applicable to all cognate molecu-lar species which share a geometrical relationship to phosphates eg sulfates perchlorates etc

Lastly we provide an Appendix as a simple guide to the application of Cahn-Ingold-Prelog Rules to label prochiral non-bridge oxygen atoms in molecules under inspection

2 Existing recommendationsPhosphorus nomenclature and related IUPAC Recommendationsa) The nomenclature of phosphorus-containing compounds of biochemical importance Recommendations

1976 was published in 1977 [17] It was concerned with the naming of compounds but did not consider the identification of the individual atoms of the phosphate or polyphosphate groups other than to label the phosphates of a nucleoside triphosphate α β and γ It did cover the naming of polyphosphates where a bridging oxygen is replaced by a methylene or imino group A variation on this was proposed in 1980 and revised in 1992 [18]

b) A document on the abbreviations and symbols for the description of conformation of polynucleotide chains Recommendations 1982 was published in 1983 [19] In a related paper it was proposed that the

140BeF3

ndash

AIF4ndash

MgF3ndash

MgF32 ndash

VO43 ndash

WO42 ndash

AIF30

120

100

80

60

40

20

0

1994

ndash199

6

1994

ndash199

9

1994

ndash200

2

1994

ndash200

5

1994

ndash200

8

1994

ndash201

1

1994

ndash201

4

1994

ndash201

7

Fig 1enspCumulative numbers of protein structures published in the PDB in successive triennia that contain ligands which are analogues of phosphoryl groups or their transition states (data for mid-2016 extrapolated to 2017)




pro-S oxygen should be OP1 and the pro-R should be OP2 [20] This is the reverse of the system proposed here and it is also contrary to CIP nomenclature where Rule 5 gives priority to R over S We have chosen to adhere to CIP priority Rule 5

c) IUPAC Recommendations for preferred names of derivatives of phosphoric acid are pertinent [21] They include the application of the CIP rules to chiral phosphates as well as CIP rules for a trigonal bipy-ramidal and octahedral systems These are also described in IUPAC inorganic chemistry nomenclature systems for bipyramidal and octahedral structures [22]

3 Recommendations for labelling phosphorus atoms in phosphates

31 A Labelling phosphorus atoms in polyphosphate species

311 A1 Species with one single polyphosphate chain

This requires a one-symbol code to describe the position of each phosphorus in a single chain of phosphates Phosphorus descriptions use a capital letter that serves to discriminate sequential phosphorus atoms in the same chain (PDB usage)a) Phosphorus atoms are named in progression from the RO- end as PA PB PG PD etc6 Hence adenosine

5prime-tetraphosphate (PDB ligand AQP) has phosphorus atoms labelled as PA PB PG PD starting from the ribose 5prime-oxygen (Fig A1a)

b) For P1-(5prime-adenosyl)-P5-(5primePrime-guanosyl) pentaphosphate (PDB Ligand G5P) phosphorus atoms should be named PA PB PG PD and PE starting at the 5prime-oxygen of the adenosine

c) For the RO- group at the end of a phosphate chain a nucleoside takes priority over a non-nucleoside Thus in uridine diphosphate glucose (PDB ligand UPG) PA is bonded to uridine-O5prime and PB is bonded to O1Prime of glucose (Fig A1b )7

d) A nucleic acid base takes priority over non-nucleic acid base (ie adenosinethinspgtthinspnicotinamide riboside) Thus in NADthinsp+ (PDB ligand NAD) PA is bonded to O5prime of adenosine with PB bonded to O5primePrime of the nicoti-namide riboside (Fig A1c)

Fig A1aensp

Fig A1bensp

6enspPDB usage currently always replaces Pγ with PG as it does not use a GreekSymbol font7enspHere and throughout negative charges on phosphates and P=O double bonds are omitted for simplicity




e) Nucleosides take priority in their alphabetical order (AthinspgtthinspCthinspgtthinspGthinspgtthinspdTthinspgtthinspU) Thus in P1-(5prime-adenosyl) P4-(5primePrime-deoxythymidyl) tetraphosphate (Ap4dT) (PDB ligand 4TA) the phosphorus atoms should be named PA PB PG PD starting at the 5prime-oxygen of the adenosine (Fig A1d)

f) Pentoses use CIP priorities D-ribosethinspgtthinspL-ribosethinspgtthinsp2-deoxy-D-ribosethinspgtthinsp2-deoxy-L-ribose8 Thus a transition state for dAMP kinase should label the four phosphorus atoms PA PB PG PD starting from the adenosine 5prime-oxygen (Fig A1e)

g) In phosphonate and phosphoramidate analogues of polyphosphates phosphorus atoms will be labelled in the same manner as for the parent polyphosphate molecule Hence for βγ-methylene-GTP (PDB ligand GCP) phosphorus atoms should be named PA PB and PG from the 5prime-oxygen (Fig A1f1)

Likewise for 2prime-deoxyuridine 5prime-αβ-imidotriphosphate (PDB ligand DUP) phosphorus atoms should be named PA PB and PG from the 5prime-oxygen (Fig A1f2)

Fig A1censp

O

HO

ThyO

PO

PO

PO

PO

O O O OO O OO

PA PG

OAde

HO OH PB PD

Fig A1densp

Fig A1eensp

Fig A1f1ensp

Fig A1f2ensp

8enspThis pentose order approximates to CIP Rule 5 priority (R)thinspgtthinsp(S) This rule will apply particularly to transition states for deoxy-nucleotide kinases eg where ATP phosphorylates dAMP




312 A2 Species with multiple single phosphate chains

This requires a one-symbol code to describe the relationship of each phosphate chain to the parent moleculea) Inositol polyphosphates require a phosphorus label derived from the identity of the oxygen to which each

single phosphate is attached Thus for myo-inositol 13456-pentakis phosphate (InsP5) (PDB ligand 5MY) the phosphorus atoms should be labelled P1 P3 P4 P5 and P6 (Fig A2a1)9 For fructose 16-bispho-sphate (PDB label FBP) the phosphorus atoms should be labelled P1 and P6 (Fig A2a2)

313 A3 Species with multiple single phosphate andor polyphosphate chains

This requires a two-symbol code to describe (i) the position of each phosphorus in a single chain of phosphates and (ii) the relationship of that phosphate chain to the parent moleculea) Species with polyphosphates located on multiple oxygen atoms require a two-symbol code to designate their

phosphorus atoms a numerical code for the oxygen bridging to the parent molecule and an alphabetic code for the position of the phosphorus in the phosphate chain Thus in pppGpp (PDB ligand 0O2) the 5prime-phos-phorus atoms should be named PA5 PB5 and PG5 and the 3prime-phosphorus atoms named PA3 and PB3 (Fig A3a)

b) Inositol polyphosphates having polyphosphate moieties require a two-symbol code to designate their phosphorus atoms A numerical symbol designates the oxygen to which each single phosphate is attached and an alphabetic code designates the position of the phosphorus in the phosphate chain In the case of monophosphates the labels P1 P2 etc should apply to single phosphorus entities while PAn and PBn will apply to diphosphates as in PP-InsP5 (PDB ligand I7P) (Fig A3b)4

Fig A2a1ensp Fig A2a2ensp

O

OH

GuaO

PO

PO

PO

O O OO O O

PB5

5prime

PG5 PA5

O PO P

O

OOO

O

PB3 PA3

3prime

Fig A3aensp

OPO3

OPO3

OPO3

OO3PO

O3PO

PO

PO

O OOO

PA5 PB5

PA1

PA2

PA3

PA4

PA6

Fig A3bensp

9enspcf R F Irvine amp M J Schell Nature Rev Molec Cell Biol 2 327ndash338 (2001)




4 Recommendations for labelling oxygen atoms in phosphates

41 B1 Non-terminal phosphates in molecules with one single phosphate chain

This requires a two-symbol code to describe (i) the identity of the oxygen relative to its congeners and (ii) the identity of the parent phosphorus atom Oxygen codes use a number first to discriminate oxygen atoms bonded to the same phosphorus followed by a letter to indicate the parent phosphorusa) The oxygen linking PA to the carbon moiety of the molecule will retain its regular label Thus in ATP O5prime

bonds PA to the ribose (Fig B1a1) In Ap4G O5prime bonds PA to adenosine while O5primePrime bonds PD to guanosine (Fig B1a2) [16]

b) In each non-terminal phosphoryl group (PO3) the bridging oxygen bonding PX to P(Xthinsp+thinsp1) in the chain should be numbered O3X Hence in ATP O3A joins PA to PB and O3B joins PB to PG (Fig B1b)

c) In each non-terminal phosphoryl group the two non-bridging oxygen atoms will be labelled 1 and 2 according to their CIP pro-R- and pro-S-chiralities respectively10 Hence in ATP PA will have non-bridging oxygen atoms O1A and O2A for the pro-R and pro-S oxygen atoms respectively (Fig B1b)

d) Bridging atoms in polyphosphate chains should be given priorities OnprimethinspltthinspO3AthinspltthinspO3BthinspltthinspO3GthinspltthinspO3Dthinspltthinspetc (Section B3) This provides a relatively direct CIP route to the assignment of paired non-bridging oxygens on non-terminal PB PG etc that can be illustrated here for O1B and O2B (Fig B1d)

e) In chains containing a sulfur atom in a non-bridging non-terminal position the sulfur will take the name S1A (for substituent on PA) S1B (for substituent on PB) etc The non-bridging oxygen is then named O2A

Fig B1a1ensp Fig B1a2ensp

Fig B1bensp

Fig B1densp

10enspThis nomenclature is widely used in the PDB for oxygen atoms on PA and PG in nucleoside triphosphates but is rather variably used for oxygen atoms on PB




O2B etc and the bridging oxygen is O3A O3B etc as above This is shown for guanosine 5prime-(Rp)-α-thio-triphosphate (PDB ligand GAV) (Fig B1e)

In modified polyphosphate chains having two-atom bridges replacing an O3N (where Nthinsp=thinspA B etc) the bridging atoms X and Y will be labelled X3A and Y4A progressively Thus in βγ-oxymethylene-ATP (AdoPOPOCH2P) the PB PG-bridging atoms are O3B and C4B respectively (Fig B1f)

In polyphosphate chains with a bridging oxygen replaced by carbon or nitrogen the prochirality11 des-ignations may change in consequence Thus in αβ-methylene adenosine 5prime-triphosphate (PDB ligand APC) (Fig B1g) oxygen atoms O1A and O2A are reversed relative to their designation in ATP (Fig B1b) because of the changed priority of C3A relative to O5prime

42 B2 Non-terminal phosphates in molecules with multiple phosphate chains

This requires a three-symbol code using (i) one symbol to describe the identity of the oxygen relative to its con-geners and (ii) two symbols for the identity of the parent phosphorus atom (see above)a) In each non-terminal phosphoryl group the two non-bridging oxygen atoms will be labelled 1 and 2

according to their CIP pro-R and pro-S chiralities respectively Hence in ppGpp (PDB ligand G4P) PA5 will have non-bridging oxygen atoms O1A5 and O2A5 for the pro-R and pro-S oxygen atoms respectively and PA3 will have non-bridging oxygen atoms O1A3 and O2A3 for the pro-R and pro-S oxygen atoms respectively12 (Fig B2a)

b) In NADthinsp+ the oxygen atoms on PA will be labelled O1A and O2A for the pro-R and pro-S oxygen atoms respectively and the oxygen atoms on PB will be labelled O1B and O2B for the pro-R and pro-S oxygen atoms respectively (Fig B2b) (NB Ade takes priority over Nicotinamide Fig A1d)

O

HO OH

GuaO

PO

PO

PO

O O SO O O5prime

O3A

S1A O2A

Fig B1eensp

O

HO OH

AdeO

PCH2

PO

PO

O O OO O O

5prime

O1AO2A

C3A

PA

Fig B1gensp

O

HO OH

AdeO

PO

PCH2O

O OO O

PO

O O

O3BC4B

Fig B1fensp

11enspAn Appendix has been added on a simple introduction to the use of CIP Rules on prochirality and the assignment of pro-R and pro-S descriptions12enspFor simplicity the designation omits the prime symbol from eg O2A3prime




c) In ppIns5p the oxygen atoms on PA5 will be labelled O1A5 and O2A5 for the pro-R and pro-S oxygen atoms respectively (Fig B2c)

d) In each non-terminal phosphoryl group (PO3) the bridging oxygen bonding PN to P(Nthinsp+thinsp1) (where Nthinsp=thinspA B etc) in the chain should be numbered O3Nx where x designates the parent oxygen of the polyphosphate chain Hence in ppGpp (PDB ligand P4G) PA5 is joined to PB5 by O3A5 and PA3 is joined to PB3 by O3A3 (Fig B2d)

43 B3 Non-terminal phosphates in molecules with a doubly-capped single phosphate chain

This requires a two-symbol code to describe (i) the identity of the oxygen relative to its congeners and (ii) one symbol for the identity of the parent phosphorus atom (vs)

There are several examples of natural and non-natural dinucleosidyl polyphosphates with phosphate chain lengths from 2 to 6 phosphates P1-(5prime-adenosyl) P4-(5primePrime-deoxythymidyl) tetraphosphate (Ap4dT) (PDB

O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA

5primeprimeprime5primeOAde

HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp




ligand 4TA) (Fig A1d) and P1-(5prime-adenosyl)-P4-(5primePrime-guanosyl) tetraphosphate (Ap4G) (Fig B1a2) have been discussed above While the accurate and sometimes tricky application of CIP rules can deliver an appro-priate descriptor for paired non-bridging oxygens for symmetrical molecules including Ap3A and Ap5A the oxygens on the central phosphate are stereochemically identical (being related by C2 symmetry) They become a diastereotopic pair only in a chiral environment as when bound to a protein for which an addi-tional Rule is needed The problem can easily be resolved by the application of an additional priority Rule for sequential phosphates in polyphosphate chains

ldquoBridging atoms in polyphosphate chains are given priorities that increase with increasing separation from the priority nucleoside oxygen OnprimethinspltthinspO3AthinspltthinspO3BthinspltthinspO3GthinspltthinspO3DthinspltthinspetcrdquoThe application of this rule is illustrated for P1-(5prime-adenosyl)-P3-(5primePrime-adenosyl) triphosphate Ap3A (Fig B3a) By extension this rule also provides a relatively direct assignment for the non-terminal phosphates of ATP p4A etc It is further illustrated in the Appendix (Section 95)

44 B4 Terminal phosphates in molecules with multiple phosphate chains

This requires a two-symbol code to describe (i) the identity of the oxygen relative to its congeners and (ii) the identity of the parent phosphorus atom (vs) The three oxygen atoms of a terminal phosphoryl group (PO3) are pro-pro-chiral They can thus be labelled according to CIP rules in those (rare) cases where they are identified by isotopes 16O 17O and 18Oa) In cases of a terminal phosphoryl oxygen being replaced by eg sulfur fluorine or nitrogen the remain-

ing two terminal oxygen atoms are prochiral and can be appropriately identified by CIP chirality rules Thus in GTPγS (PDB ligand GSP) the sulfur has priority to be labelled S1G and the oxygen atoms are labelled O2G (pro-R) and O3G (pro-S) respectively (Fig B4a)

b) Prochirality identification can be applied if one of the three oxygen atoms is promoted relative to the other two In the context of enzyme-bound nucleotides such promotion can often be identified by co-ordination of the terminal phosphate to a protein-bound metal ion typically magnesium Thus for ATP bound in many kinases the γ-phosphate is coordinated from one of its three oxygen atoms to magnesium This oxygen is thus designated O1G The remaining oxygen atoms are now prochiral and can be identified in the priority series O3BthinspgtthinspO1GthinspgtthinspO2GthinspgtthinspO3G CIP rules then designate O2G as the pro-R oxygen and O3G as the pro-S oxygen as illustrated for ATP bound in phosphoglycerate kinase (Fig B4b PDB entry 1VJC)

c) In the absence of metal ion coordination to the terminal phosphate H-bond donation from amino acids in the protein provides a means of priority identification for O1N Hydrogen bonds are considered only

Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp




if they have a length le thinsp30 Aring13 Priority will be given according to donor atom XH priority with CIP rules (SthinspgtthinspOthinspgtthinspN) Hydrogen bonding to the amino acid of lowest primary sequence number will identify O1G in ATP etc If there is still ambiguity in the assignment then backbone NH takes priority over sidechain NH14 This selection makes O2G and O3G prochiral hence they can be assigned by the application of CIP rules15 Thus in human bisphosphoglycerate mutase (PDB entry 2A9J) the 3-phosphoglycerate has phosphoryl oxygen coordination from Arg100 and Arg116 to O1A from Arg117 and Asn190 to O2A and from Arg117 to O3A (Fig B4c1) After O1A is promoted by amino acid linkage priority O2A and O3A are assigned by prochirality rules (O3thinspgtthinspO1AthinspgtthinspO2AthinspgtthinspO3A)

In the case of human protein tyrosine phosphatase ptpn5 (C472S mutant) the tyrosine phosphate moiety is coordinated to residues in the loop Ala474-Arg478 (PDB entry 2CJZ) Consideration of hydrogen bonds le thinsp30 Aring shows oxygen O1P coordinated to Gly477 and Ile476 oxygen O2P coordinated to Ala474 and Arg478 and oxygen O3P coordinated to Arg478 Thus we can now designate O1A as being coordinated to the lowest numbered amino acid Ala474 (it is labelled as O2P in 2CJZ)10 The oxygen atom priority is O4primethinspgtthinspO1AthinspgtthinspO2AthinspgtthinspO3A in which O2A and O3A are designated by CIP rules for prochirality10 as shown (O2A being pro-R and O3A is pro-S) (Fig B4c2) (NB There are H-bonds from Ser472(OH) to O2P and O3P but both are longer than 30 Aring and thus are ignored distance from heavy atom to heavy atom)


This requires a three-symbol code (i) one symbol to describe the identity of the oxygen relative to its congeners and (ii) two symbols for the identity of the parent phosphorus atom (vs)

Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp

13enspThe Aringngstrom as the unit of distance in protein structures is standard throughout biochemistry bioorganic chemistry and molecular biology The IUPAC use of nm as the IS unit of sub-micrometer distance is readily accommodated by the conversion factor 1 nmthinsp=thinsp10 Aring14enspIn determining priorities coordination to an isolated water is ignored because the presence or absence of a particular isolated water in a crystal structure can be a function of the structural resolution achieved which makes water a variable object However waters coordinated to metal ions can be used15enspFor CIP Rules see the IUPAC Blue Book p1162 [21] For the use of pro-R and pro-S see ldquoBasic Terminology of Stereochemistry (IUPAC Recommendations 1996)rdquo Pure Appl Chem 68 2193ndash2222 (1996)

O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp




a) The rules described above (section B3) for single phosphate chains will apply with the addition of a descriptor symbol designating the point of attachment of that chain to the parent molecule Thus for human aldolase reductase (PDB entry 2J8T) the bound NADPthinsp+ (PDB ligand NAP) has the oxygen atoms of PA2 coordinating no metal and hydrogen bonded to Lys262 Ser263 Val264 Thr265 and Arg268 Thus the oxygen coordinating Ser263 takes priority and is named O1A2 The oxygen atom priorities for PA2 are thus O2thinspgtthinspO1A2thinspgtthinspO2A2thinspgtthinspO3A as shown (Fig B5a)

46 B6 Isolated single phosphates

This requires prioritisation of two oxygen atoms by their coordination features thus allowing the third and fourth oxygen atoms to be assigned their prochirality by CIP rules

Isolated phosphate with no metal ions In a structure of the small G protein Rab-5c with GDP and Pi ligands in the catalytic site (PDB entry 1Z0D) the isolated phosphate (PDB ligand PO4) is not metal coordi-nated Thus the relative priorities of its 4 oxygen atoms are determined by H-bonds to amino acid residues Ignoring H-bonds ge thinsp30 Aring the PDB file assigns O1 coordinated to Ser30(OH) O2 coordinated to Leu80(NH) and O3 coordinated to Lys34(NH3

thinsp+) O4 is only coordinated to ligands at distances ge thinsp30 Aring (oxygen atoms numbered as in 1Z0D) (Fig B6a) (Hence the PDB priority order is O1thinspgtthinspO3thinspgtthinspO2thinspgtthinspO4)

Assigning the top two oxygen priorities as O1P and O2P respectively (Fig B6b) converts the two remaining oxygen atoms into a prochiral pair Promoting the lsquofrontrsquo oxygen to 18O gives phosphorus S chirality thus identify-ing it as pro-S (O4P) By a similar analysis the lsquorearrsquo oxygen (H-bonded to Leu80) is pro-R Hence the rear oxygen is designated O3P and the front oxygen is O4P (Fig B6b) (NB The PDB file assigns PA and PB to the GDP ligand)

5 Recommendations for labelling fluorine and other atoms in phosphate transition state analogues

51 C1 Tetrahedral phosphate mimics ndash trifluoroberyllates

These use a two-symbol code that may be expanded to four when there are additional fluorine atoms in the species

O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp




a) There are over 100 examples of trifluoroberyllates (BeF3thinspminus) in the PDB (PDB ligand BEF) This phosphate

mimic is invariably attached to a carboxylate or terminal phosphate oxyanion Labelling the three fluo-rine atoms will follow the same rules as for the three oxygen atoms in a terminal tetrahedral phosphate Prochirality10 identification can be applied if one of the three fluorine atoms is promoted relative to the other two In the context of enzyme-bound trifluoroberyllates such promotion can be generally identi-fied by co-ordination of one of the fluorine atoms to a protein-bound metal ion typically magnesium For example in β-phosphoglucose mutase (PDB entry 2WF8) a BeF3 is coordinated to Asp8 while a catalytic magnesium bridges Asp8 and one fluorine This fluorine is thus identified as F1Be The prochiral fluorine atoms F2Be and F3Be are designated by CIP rules as shown in the example (Fig C1a) As there is no other fluorine in this structure these labels can be abbreviated to F1 F2 and F3 respectively(Note that in PDB entry 2WF8 these fluorine atoms were labelled F3 F1 and F2 respectively)

There is one example of a BeF2 moiety bridging two anionic oxygen atoms In this case F1Be and F2Be will correspond to the (pro-R) and (pro-S) stereochemistry assigned by CIP rules Thus in UMPCMP kinase (PDB entry 4UKD) BeF2 bonds to ADP O3B and to UDP O3G (Fig C1b) Thus the (pro-R) fluorine is F1Be and the (pro-S) fluorine is F2Be16 In this unique and rather complicated example CIP rules give priority to O5prime over O5primePrime since adenine (A) takes priority over uridine (U) (Section A1d)

b) There may be less common species where there is no metal ion coordinating the trifluoroberyllate In these the hydrogen bonding priorities set out in B3c can be applied

c) In an example of multiple metal coordination where the distances of separation from both metals to fluorine are less than the sum of the two van der Waals radii the coordinating metal with higher atomic number will take priority

52 C2 Trigonal bipyramidal phosphate transition state analogues ndash trifluoromagnesates and aluminum trifluorides

This requires a two-symbol code to describe (i) the identity of the fluorine relative to its congeners and (ii) the identity of the core metal iona) For AlF3 (PDB code AF3) MgF3 (PDB code MGF) and ScF3 tbp transition state analogues (TSA) the three

fluorine atoms are invariably equatorial with two axial oxygen ligands to the 5-coordinate metal Priority

Fig C1aensp

16enspIn the case of an (as yet unidentified) symmetrical species the priority of the two equivalent fluorine atoms will be based on ligand coordination as shown in Sections C2b and C3c below

AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE

O5prime O5primeprimeprimeO3G

F1BeF2Be

O3B

Fig C1bensp




identification can be applied when one of the three fluorine atoms is promoted relative to the other two and directional priority for the two axial ligands is established In the context of enzyme-bound trifluo-romagnesates and aluminates such promotion is readily identified by closest proximity of one fluorine to a protein-bound metal ion typically a catalytic magnesium The direction of viewing is determined by CIP priority of one of the apical (oxygen) atoms over the second viewing down the priority O-metal bond Thus in the small G protein Ras (PDB entry 1OW3) MgF3 is axially coordinated to GDP via O3B and to a water and CIP priority gives O3BthinspgtthinspOH2 Thus the fluorine coordinated to the catalytic magnesium is designated F1Mg F2Mg and F3Mg are then identified in a clockwise progression from F1Mg when viewed from O3B to Mg (Fig C2a)17

b) In case of multiple metal ion coordination where both distances of separation are less than the sum of the two van der Waals radii the coordinating metal with highest atomic number will take priority In cases where two fluorine atoms are coordinated to two equivalent metals as for cAPK (PDB entry 1L3R) in which the tbp complex of ADPthinspmiddotthinspMgF3 is liganded to two catalytic magnesium atoms F1Mg is prioritised as the fluorine coordinated to the magnesium of higher priority Metal priority shall be determined by its amino acid coordination (see Section B3c) Viewing priority is determined by O3BthinspgtthinspO-Ser21prime In cAPK one catalytic magnesium is coordinated to Asn171 to Asp184 and to a water the second magnesium is coordi-nated to Asp184 and to two waters Hence the magnesium linked to Asn171 has priority and is coordinated to F1Mg F2Mg and F3Mg follow in clockwise progression (Fig C2b)

c) In the absence of fluorine coordination to a metal hydrogen bonding to amino acids can be used to deter-mine fluorine priority (see section B4c)18

d) A significant number of structures in the PDB (gtthinsp24) have a trigonal bipyramidal complex assigned as tetra-fluoromagnesate(2thinspminusthinsp) (PDB ligand MF4) The best resolved of these (PDB entry 1WPG 230 Aring resolution) has electron density and bond lengths that can be equally well assigned as a regular Asp351-CO2

thinspminusthinspmiddotthinspMgF3thinspminusthinspmiddotthinspOH2

complex This can be labelled as for C2a (above) using coordination to a catalytic Mg to give priority to F119

5prime

Fig C2aensp

Fig C2bensp

17enspNB These fluorine atoms are labelled F2 F1 and F3 respectively in PDB entry 1OW3 (Viewing indicated by magenta arrow)18enspNo example of a tbp complex of AF3 or MGF (PDB ligand identities for AlF3 and MgF3

thinspminus respt) having a coordinating divalent metal at good resolution has been lodged in the PDB prior to December 2015)19enspNo analytical work has been yet presented to identify the number of fluorides eg by 19F NMR




53 C3 Octahedral phosphate transition state mimics

This requires a two-symbol code to describe (i) the identity of the fluorine relative to its congeners and (ii) the identity of the core metal iona) For tetrafluoroaluminate AlF4

thinspminus octahedral TSA analogues (PDB ligand ALF) the four fluorine atoms are invariably equatorial with two trans-oxygen ligands to the 6-coordinate aluminium Priority identifica-tion can be applied by promoting one of the four fluorine atoms relative to the other three In the context of enzyme-bound tetrafluoroaluminates such promotion is invariably identified by closest proximity of one fluorine to a protein-bound metal ion usually magnesium The direction of viewing is determined by CIP priority of one of the apical oxygen atoms over the second and viewing down the priority O-metal bond Thus in the structure of βPGM (PDB entry 4C4R) the fluorine coordinated to the catalytic magne-sium is identified as F1Al while F2Al F3Al and F4Al follow in clockwise progression viewed from Asp8ndashOd1 which has priority over glucose-O6 (NB The corresponding PDB designations are F2 F1 F3 and F4 respec-tively)20 (Fig C3a)

b) There are at least 3 examples of octahedral trifluoroaluminate complexes (in PDB to 2015) having three fluorines in equatorial positions with the fourth equatorial ligand identified as oxygen An example of this is the transition state analogue for enzymatic hydrolysis of dUTP (PDB entry 4DL8) Axial priority for viewing is established by the CIP precedence of O3AthinspgtthinspOWat401 (Fig C3b) One fluorine is coordinated to two catalytic magnesium atoms and so is designated F1B A progression viewed in the priority direction then identifies the bridging oxygen as the second priority ligand O1B with F2B and F3B completing the clockwise equatorial sequence

c) In case of multiple metal coordination the coordinating metal with highest atomic number will take pri-ority where the distance of separation is less than the sum of the two van der Waals radii (as for Fig C2b above)

d) In the absence of fluorine coordination to a metal hydrogen bonding to amino acids will be used to determine fluorine priority Thus in the fructose 26-bisphosphatase reaction of the enzyme PFKFB3 an AlF4

thinspminus complex with His253Ne2 has been described (PDB entry 3QPW Fig C3c) This octahedral complex is completed by water coordination trans to the histidine nitrogen The four fluorine atoms are coordinated F1 to water F2 to Arg252 and Gln388 F3 to His387 and water and F4 to Arg252 and Asn259 (fluorines numbered as in

Fig C3aensp

Fig C3bensp

20enspIn cases where there are no other fluorines in the system the Al designation may be omitted




PDB 3QPW) As F2 is coordinated to Ne of Arg252 and F4 is coordinated to Arg252-NH1 F2 takes priority since its H-bonding is to the nitrogen nearer to Cα of the lowest numbered coordinating amino acid Hence F1Al is coordinated to Arg252 and Gln388 and the progression to F2Al F3Al and F4Al proceeds clockwise as viewed from the water apex of the octahedral complex (CIP priority is OthinspgtthinspN magenta arrow) (Fig C3c)21

6 Recommendations for labelling vanadate and tungstate analogues of phosphates

61 C4 Vanadates

Orthovanadate VO43thinspminus

is encountered as an analogue of phosphate in a variety of forms They are invariably trigonal bipyramidal and thus mimic a five-coordinate phosphoryl transfer processa) Monosubstituted vanadate (V) In isolation vanadate (PDB ligand VO4) can mimic the transition state

for phosphoryl group transfer as a trigonal bipyramidal complex substituted by either one or two axial oxygen ligands that represent nucleophile and leaving group A typical example is the Xac nucleotide pyrophosphatasephosphodiesterase structure (PDB entry 2GSO) where the vanadate is axially coordi-nated to Thr90 The three equatorial oxygen atoms are numbered O1V O2V and O3V with the axial oxygen O4V being trans to the hydroxylic oxygen of Thr90 (Fig C4a) The equatorial oxygen coordinated to two zinc ions takes priority and is O1V The direction of viewing is determined by the priority Thr90 oxygenthinspgtthinspO4V (magenta arrow) Thus a clockwise progression identifies O2V at the front and O3V at the rear of the trigo-nal planar array

Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp

21enspCoordination to an oxygen of an isolated water is ignored This is because the presence or absence of water in a PDB structure may be a function of the resolution of the structure and therefore may vary from one structure to another of the same protein-ligand complex Also note the use of PDB style numbering for atoms in amino acids (which avoids the use of Greek symbols)




b) Disubstituted vanadate A transition state analogue complex for phosphorylation of glucose 1-phos-phate on O6 by α-phosphoglucomutase has vanadate linearly coordinated by oxygen-3 of Ser116 and by oxygen-6 of glucose 1-phosphate (PDB entry 1C4G) CIP priority analysis gives O6GthinspgtthinspO3S The three equa-torial oxygen atoms take priority from O1V by its coordination to cobalt which substitutes for a native catalytic magnesium Assignment of O2V and O3V follows a clockwise progression when viewed from O6G (magenta arrow) (Fig C4b)

For the nucleoside-diphosphate kinase from B burgdorferi a vanadate transition state complex links ADP and His134 as axial ligands (PDB entry 4DZ6) There is no catalytic metal to coordinate the three equatorial oxygen atoms Thus oxygen H-bonded to Lys13 takes priority as O1V over oxygen O2V H-bonded to Arg94 while O3V is not H-bonded to any amino acid These assignments are in accord with those in the PDB entry

c) Trisubstituted vanadate Tyrosyl-DNA phosphodiesterase (Tdp1) is a DNA repair enzyme that catalyzes the hydrolysis of a phosphodiester bond linking a tyrosine residue to a DNA 3prime-phosphate Orthovanadate is central in a transition state analogue structure in which vanadium is linked to the tyrosine oxygen to the 3prime-oxygen of the scissile nucleotide and to His262 of the enzyme (PDB entry 1RFF) Axial ligand priority is Tyr-OthinspgtthinspHisNε2 Equatorial ligand priority is assigned to Thd-O3prime Hence O2V and O3V follow in a clockwise progression when viewed from the Tyr-oxygen (Fig C4c)

d) Cyclic trisubstituted vanadate Trisubstituted vanadate provides a transition state analogue structure for hairpin ribozyme cleavage of a phosphodiester (PDB entry 1M5O) The axial O2prime has CIP priority over the axial O5prime Priority in the three equatorial oxygen atoms is taken by the ribose-O3prime leading to assign-ment of O1V followed by O2V in a clockwise progression (Fig C4d)

Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates

Tungstate(VI) ion WO4thinsp= (PDB ligand code WO4) is a mimic of tetrahedral phosphate in a small but significant

range of structures in the PDB In such systems two oxygen atoms need to be assigned priority to enable the remaining two to be assigned by prochirality rulesa) Isolated tungstate(VI) with two metal ions In a structure of purple acid phosphatase (PDB entry

3KBP) an isolated tungstate(VI) ion mimics phosphate It is coordinated both to zinc and to iron Zinc with atomic number 30 takes CIP priority over iron (atomic number 26) and so the two tungstate oxygen atoms coordinated to these metal ions are labelled O1W and O2W respectively (Fig C5a) The remaining two tungstate oxygen atoms are now prochiral and can be labelled O3W and O4W by CIP rules described above

b) Isolated tungstate(VI) with one metal ion In a structure of a tungstate complex of CheYN59DE89R the isolated tungstate(VI) ion is coordinated to manganese and several amino acids (PDB entry 3RVS) Thus O1W is identified by its coordination to manganese Coordination to oxygen gives precedence over coordination to nitrogen Coordination to oxygen is only considered if the distance of the heavy atoms le thinsp30 Aring (see Section B3c) Hence O2W is coordinated to Asp59 and takes precedence over the third oxygen that is coordinated to Thr87 The remaining two tungstate oxygen atoms are now prochiral and can be labelled O3W and O4W by CIP rules described above (Fig C5b)

c) Isolated tungstate(VI) with no metal ion For an isolated WO4thinspminus species a similar procedure of prioriti-

sation by amino acid coordination can be used to identify O1W and O2W O3W and O4W can then be assigned by the prochirality procedure Thus in a structure of Yersinia enterocolitica PTPase complexed with tung-state (PDB entry 3F9A) an isolated tungstate is encircled by a loop of amino acids 404ndash409 with three of its oxygen atoms coordinated to NHs As isolated water coordination is ignored22 priority is given to coordination from Arg404 to O1W followed by coordination from Val407 to O2W Hence O3W and O4W are now prochiral and can be assigned using CIP rules (Fig C5c)

Fig C5aensp

Fig C5bensp

22enspNote that once coordination has reduced the number of non-prioritised oxygen atoms to two this pair is assigned by applica-tion of CIP rules on prochirality




d) Tungstate(VI) coordinated to a substrate ligand A compound example of tungstate as a dual ana-logue of phosphate is found in the structure of a protein of the histidine triad family in which adenosyl 5prime-ditungstate (PDB ligand ADW) an analogue of ADP is coordinated to His112 (PDB entry 1KPE) This situation calls for labelling both tungstens and seven oxygen atoms since the first tungstate is a trigonal bipyramidal TSA of PA and the second tungstate is a tetrahedral analogue of PB of ADP Tungsten WA is equatorially linked to the adenosyl 5prime-oxygen and axially linked to His112-Nt23 As in the case of polyphos-phates (Section B1c) the bridging oxygen to WB is designated O3A This enables the assignment of the two prochiral equatorial oxygen atoms as O1A and O2A (when viewed in the axial direction O3A to Nt) For WB oxygen O3A has highest CIP priority because it is coordinated to WA The oxygen coordinated to Gly105 takes precedence over the oxygen coordinated to Ser107 and is therefore identified as O1B This enables the prochiral pair of oxygen atoms to be assigned as O2B and O3B as shown (Fig C5d)

7 SummaryThe recommendations presented here have been developed to describe molecules derived from orthophos-phoric acid and its derivatives analogues and transition state analogues We have built on the existing usage of nomenclature wherever possible especially on Cahn-Ingold-Prelog Rules We have introduced only one Rule to override CIP analysis and that for the purpose of simplicity of use by non-experts in stereochemistry In our experience the recommendations have worked well for the most demanding species we have exam-ined eg C3c and C5d However we recognise that the recommendations may be equally relevant to other species with tetrahedral geometry such as sulfates and sulfonamides or with tbp or octahedral geometries We also recognise that there may be existing or as yet non-existent structures that could require an exten-sion of these recommendations and we remain receptive for advice on such problems

Funding International Union of Pure and Applied Chemistry (GrantAward Number lsquoUSD 10000rsquo)

Fig C5censp

Fig C5densp

23enspThe PDB description of Nt is Ne2




Appendix ndash A guide for the use of Cahn-Ingold-Prelog rules for prochiralityShort procedure for identification of paired non-bridging oxygen atoms (or paired fluorine atoms) using Cahn-Ingold-Prelog Rules for prochirality (enantiotopicity)1 Two non-bridging oxygen atoms bonded to the same phosphorus are enantiotopic if promoting one of them

from isotope-16 to isotope-18 generates the opposite enantiomer compared to promotion of the other24 This is illustrated for methyl phenylphosphonate (Fig X1) Promoting the lsquofrontrsquo oxygen (Step a) gives molecule (A) where the phosphorus is a stereogenic centre and is labelled R in Cahn-Ingold-Prelog nomenclature Promoting the lsquorearrsquo oxygen (Step b) gives molecule (B) where the stereogenic phosphorus is labelled S This analysis is based on the CIP priority rule O(Me)thinspgtthinsp18Othinspgtthinsp16OthinspgtthinspC on viewing the face of the P-centered tetra-hedron with the lowest priority ligand (C) at the rear (magenta arrow) a clockwise progression from high to low priority is designated R (as shown) and an anticlockwise progression is S Because A and B are enan-tiomers the two non-bridge oxygen atoms are enantiotopic In extension the paired non-bridge oxygen atoms can be labelled (pro-R) for the front one (clockwise progression) and (pro-S) for the rear one (C right)

2 Two non-bridging oxygen atoms bonded to the same phosphorus are diastereotopic if promoting one of them from isotope-16 to isotope-18 generates a different diastereoisomer compared to promotion of the other25 In the case of adenosine 5prime-diphosphate (ADP) the two non-bridging paired oxygen atoms on PA are diastereotopic Promoting the lsquofrontrsquo oxygen to 18O generates a new stereogenic centre at PA (D CIP label S) while promoting the lsquorearrsquo oxygen to 18O generates a stereogenic centre with the opposite sense at PA (E CIP label R) (Fig X2) NB the D and E stereoisomers are not mirror images because the stereochem-istry of the D-ribose is unchanged Since they are not enantiomers they are termed diastereoisomers26

3 We can now apply the priority rules described in Section X1 to label the non-bridging oxygen atoms on PA in ADP This analysis begins with the CIP priority rule that ranks di-coordinate oxygen above mono-coordinate oxygen Thus O5prime and O3A rank above the two non-bridging oxygen atoms For these bridging oxygen atoms relative priority is determined by the next atom in the chain priority is given to the atom with the higher atomic number In the case of ADP the sub-adjacent atoms along the chain are PB and C5prime Hence O3A has priority over O5prime as P has a higher atomic number than C The CIP priority ranking is thus O3AthinspgtthinspO5primethinspgtthinsp18Othinspgtthinsp16O (Fig X3)27

Fig X1ensp

Fig X2ensp

24enspThese oxygen atoms are spectroscopically and chemically non-equivalent in a chiral environment25enspThese oxygen atoms are spectroscopically and chemically non-equivalent in any environment26enspThe term diastereoisomer simply embraces all stereoisomers that are NOT enantiomers27enspNB Labelling a non-bridge oxygen with 18O only gives it priority over the 16O oxygen It does not change its priority relative to the non-bridging oxygen atoms




Viewing the P-centered tetrahedron in stereoisomer (D) from the face with 16O at the rear gives an anti-clockwise progression from high to low priority ligands (Fig X3 left) and so PA in D has S-configuration Hence the two paired-oxygen atoms in ADP can be labelled pro-S for the front one (as its promotion to 18O makes PA an S chiral centre) and pro-R for the rear one (as its promotion to 18O makes PA an R chiral centre) (Fig X3 center) We can now apply CIP Rule 5 that gives R priority over S Thus the pro-R oxygen is labelled O1A and the pro-S oxygen is labelled O2A (Fig X3 right)

4 The rigorous application of the CIP rules almost inevitably means that there are unexpected outcomes For example the stereochemistry of the non-bridging oxygen atoms at PB in guanosine 5prime-triphosphate (GTP) and in γ-thioGTP (GSP) have opposite assignments For GTP the rules for the in-chain atoms flank-ing PB identify O5prime bonded to C5prime thereby taking priority over all oxygen atoms bonded to PG (O1G O2G O3G) Hence the priority sequence for the four GTP oxygen ligands at PB is O3AthinspgtthinspO3B and thus the front oxygen is pro-R and the rear oxygen is pro-S (Fig X4a) Hence the pro-R oxygen is labelled O1B and the pro-S oxygen oxygen is O2B (Fig X4a)By contrast for GTPγS the sulfur atom on PG takes CIP priority over O5prime with the consequence that O3A takes priority over O3B (Fig X4b) The result is that in GTPγS (as presented) the rear oxygen is pro-R (and thus O1B) and the front oxygen is pro-S (and thus O2B) (Fig X4b) This is the opposite 3D spatial outcome compared to GTP We note that a like situation holds for GTPγF but not for γ-amino-GTP

5 The above problem is readily resolved by a user-friendly solutionThe practical use of these interlinked analogues of nucleoside triphosphates especially for ATP and GTP calls for a simplified nomenclature system designed to deliver comparable labels for diaste-reotopic oxygens on non-terminal phosphates across the series of phosphoramidate phosphonate phosphofluoridate and phosphorothioate analogs of NTPs That can be achieved by the use of a new nomenclature rule that gives priority to bridging oxygens in an extended polyphosphate chain based simply on their position in the chain rather than on their often convoluted substituent atom prioritiesldquoBridging atoms in polyphosphate chains should be given priorities that increase with separation from the priority nucleoside oxygen OnprimethinspltthinspO3AthinspltthinspO3BthinspltthinspO3GthinspltthinspO3Dthinsplt etcrdquoThis rule already described and used in Section 4B1d is applied here to resolve the nomenclature dis-crepancy for O1B and O2B encountered in structures X4ab (above) In the case of GTP analogs having O3G replaced by another heavy atom the rule assigns priorities as O3BthinspgtthinspO3AthinspgtthinspO1BthinspgtthinspO2B (Fig X5a) This now

Fig X3ensp

Fig X4aensp Fig X4bensp




assigns the same descriptors to the prochiral oxygens at PB as that in Fig X4b (and the contrary to that for Fig X4a)

The simplicity of use of this rule is also illustrated in naming the diastereotopic pairs of oxygens on PA PB and PG for adenosyl-5prime tetraphosphate p4A (Fig X5b) The priority order for the bridging oxygens OnprimethinspltthinspO3AthinspltthinspO3BthinspltthinspO3G results in a consistent naming for the non-bridging oxygens relative to their spatial location as O1A O1B and O1G (all frontal) and O2A O2B and O2G (all rearwards) (Fig X5b)

Membership of the sponsoring bodyMembership of the IUPAC Organic and Biomolecular Chemistry Division Committee for the period 2014ndash2015 is as follows

President M J Garson (Australia) Vice President M A Brimble (New Zealand) Secretary A Gries-beck (Germany) Past President K N Ganesh (India) Titular Members G Blackburn (UK) A Brandi (Italy) T Carell (Germany) B Han (China) F Nicotra (Italy) N E Nifantiev (Russia) Associate Members A Al-Aboudi (Jordan) V Dimitrov (Bulgaria) J F Honek (Canada) P Maacutetyus (Hungary) A P A E Knight Total internal reflection fluorescence microscopy 1319 Rauter (Portugal) Z Xi (ChinaBeijing) National Representatives Y-M Choo (Malaysia) O M Demchuk (Poland) M Ludwig (Czech Republic) V Milata (Slovakia) M Olire Edema (Nigeria) P M Pihko (Finland) N Sultana (Bangladesh) H Vanik (Croatia) B-J Uang (ChinaTaipei) T Vilaivan (Thailand)

Membership of the IUPAC Organic and Biomolecular Chemistry Division Committee for the period 2016ndash2017 is as follows

President MA Brimble (New Zealand) Vice President F Nicotra (Italy) Secretary A Rauter (Por-tugal) Past President M Garson (Australia) Titular Members P Andersson (Sweden) J Clardy (USA) N Nifantiev (Russia) G Pandey (India) J Scott (UK) Chen Xi (China) Associate Members V Bolzani (Brazil) T Carell (Germany) E Uggerud (Norway) O Demchuk (Poland) N M Carballeira (Puerto Rico) B Sener (Turkey) National Representatives E Naydenova (Bulgaria) Ken-Tsung Wong (ChinaTaipei) M Ludwig (Czech Republic) S Marque (France) A Al-Aboudi (Jordan) I Shin (Korea) K Lammertsma (Neth-erlands) M Ali Munawar (Pakistan) V Milata (Slovakia) L Mammino (South Africa)

References[1] J R Knowles Annu Rev Biochem 49 877 (1980)[2] G Lowe Acc Chem Res 16 244 (1983)[3] R S Cahn C Ingold V Prelog Angew Chem 78 413 (1966)[4] R S Cahn C Ingold V Prelog Angew Chem Int Ed Engl 5 385 (1966)[5] G A Orr J Simon S R Jones G J Chin J R Knowles Proc Natl Acad Sci USA 75 2230 (1978)[6] K-F Sheu P A Frey J Biol Chem 253 378 (1978)





[7] R L Jarvest G Lowe J Chem Soc Chem Commun 364 (1979)[8] S R Jones L A Kindman J R Knowles Nature 275 (5680) 564 (1978)[9] M W Bowler M J Cliff J P Waltho G M Blackburn New J Chem 34 784 (2010)

[10] S C Kamerlin P K Sharma R B Prasad A Warshel Quart Revs Biophys 46 1 (2013)[11] G M Blackburn Y Jin N G J Richards JP Waltho Angewandte Chemie Int Ed (2016) doi 101002anie201606474[12] N J Baxter L F Olguin M Goličnik G Feng A M Hounslow W Bermel G M Blackburn F Hollfelder J P Waltho

N H Williams Proc Natl Acad Sci USA 103 14732 (2006)[13] N J Baxter G M Blackburn J P Marston A M Hounslow M J Cliff W Bermel N H Williams F Hollfelder

D E Wemmer J P Waltho J Am Chem Soc 130 3952 (2008)[14] Y Jin M J Cliff N J Baxter H R W Dannatt A M Hounslow M W Bowler G M Blackburn J P Waltho Angew Chem

Int Ed 51 12242 (2012)[15] J Mishra U S Bhalla Biophys J 83 1298 (2002)[16] M A G Sillero A de Diego E Silles F Peacuterez-Zuacutentildeiga A Sillero FEBS Lett 580 5723 (2006)[17] Nomenclature of Phosphorus-Containing Compounds of Biochemical Importance (Recommendations 1976) IUPAC-IUB

Commission on Biochemical Nomenclature Proc Natl Acad Sci USA 74 2222 (1977)[18] International Union of Biochemistry and Molecular Biology Biochemical Nomenclature and related documents 2nd edition

Portland Press 1992 109ndash114 256ndash264 and 335 [ISBN 1-85578-005-4] (see also IUPAC-IUB Joint Commission on Biochemical Nomenclature Pure Appl Chem 55 1273ndash1280 (1983))

[19] Abbreviations and symbols for the description of conformations of polynucleotide chains Recommendations 1982 Eur J Biochem 131 9 (1983)

[20] Newsletter of the Nomenclature Committees of the International Union of Biochemistry and Molecular Biology Eur J Biochem 122 437 (1982) [also ref 12 p 265]

[21] IUPAC Nomenclature of Organic Chemistry IUPAC Recommendations and Preferred Names 2013 (H A Favre W H Powell Eds) Royal Society of Chemistry Cambridge UK (2014) (a) P-9324 p 1215 (b) P-93335 p 1222ndash1223 (c) P-93337 p 1225ndash1226 H A Favre W H Powell Royal Society of Chemistry (2013) Corrections httpwwwchemqmulacukiupacbibliogBBerrorshtml p 432ff P-423-4 Phosphorus acids etc p 915ff P-67 Phosphorus acids etc p 992ff P-683 Phosphorus compounds p 1215ff P-9324 Stereochemistry of phosphates etc p 1420ff P-105 Nucleosides p 1425ff P-106 Nucleotides

[22] Nomenclature of Inorganic Chemistry IUPAC Recommendations 2005 Royal Society of Chemistry (2005) Corrections httpwwwchemqmulacukiupacbibliogRBcorrecthtml which has links to later corrections PDFhttpwwwiupacorgnchomepublicationsiupac-booksbooks-dbbook-detailshtmltx_wfqbe_pi1[bookid]=5 p180ff IR 9334 octahedral coordination p184ff IR 9336 bipyramidal coordination p 189ff IR 9338 chiral octahedral p 190ff IR 93310 chiral bipyramid




3 RECOMMENDATIONS FOR LABELLING PHOSPHORUS ATOMS IN PHOSPHATES 6564 RECOMMENDATIONS FOR LABELLING OXYGEN ATOMS IN PHOSPHATES 6595 RECOMMENDATIONS FOR LABELLING FLUORINE AND OTHER ATOMS IN

PHOSPHATE TRANSITION STATE ANALOGUES 6646 RECOMMENDATIONS FOR LABELLING VANADATE AND TUNGSTATE ANALOGUES

OF PHOSPHATES 6687 SUMMARY 671 APPENDIX ndash A GUIDE FOR THE USE OF CAHN-INGOLD-PRELOG RULES FOR PROCHIRALITY 672 MEMBERSHIP OF THE SPONSORING BODY 674 REFERENCES 674

1 IntroductionThe advent of stereochemical studies on phosphate esters and diesters with particular reference to their enzyme catalysed reactions initially through the work of Knowles [1] and of Lowe [2] placed new demands on the nomenclature of the oxygen atoms of the transferring phosphoryl group PO3

thinspminus1 In early work employ-ing thiophosphates made chiral by the specific introduction of oxygen-18 paired with oxygen-16 the direct application of Cahn-Ingold-Prelog (CIP) Rules for prochirality [3 4] resolved the problem by labelling the oxygen atoms (Rp) and (Sp) as appropriate [5ndash7] The more advanced use of 16O 17O and 18O bonded to the same phosphorus [8] led to the concept of pro-pro-pro-chirality at phosphorus which was still capable of CIP identification [2 8] However such isotopic labelling is experimentally demanding and not necessarily appli-cable to stereochemical problems now more readily amenable to analysis through advances in protein crys-tallography The increasing frequency of binary and tertiary structures of proteins in complex with phosphate ester substrates andor analogues has enabled a rapidly expanding number of enzyme catalysed reactions to be investigated by structural and computational methods [9ndash11] Indeed there are now over 1600 ligands in the PDB having a phosphoryl group component These are associated with over 28 000 deposited structures While many of these structures can be and have been labelled for their phosphorus and phosphoryl oxygen atoms through current practice comparative studies of related structures easily identify multiple inconsist-encies in labelling that arise from variable methods of naming N O and P atoms

This situation has become increasingly complex as a result of the introduction and development of metal fluoride (MFx) analogues of the PO3

thinspminus group in studies on transition state analogues (TSA) for phosphoryl transfer enzymes Trifluoroberyllate (BeF3

thinspminus)2 is a ground state analogue for phosphate with characteristic tetrahedral geometry when ligated to anionic oxygen Tetrafluoroaluminate (AlF4

thinspminus)3 is a mimic for concerted phosphoryl transfer in multiple enzymes though it has octahedral geometry Aluminium trifluoride (AlF3)4 forms trigonal bipyramidal (tbp) TSA complexes that have the correct 3-D geometry for concerted PO3

thinspminus group transfer but lack its anionic charge These two values converge in the relatively smaller number of trifluoro-magnesate complexes (MgF3

thinspminus)5 which are both anionic and have tbp geometry Indeed some of the AlF3 com-plexes have been shown in reality to be MgF3

thinspminus complexes in solution [12ndash14] The growth in use of these four types of MFx complexes is illustrated in Fig 1 In addition there are many significant structures of phosphoryl transfer enzyme complexes that include vanadium(V) or tungsten(VI) complexes either as tetrahedral phos-phate mimics or as tbp mimics of transition states The relative growth in use of these six species is presented in Fig 1 The double change from four coordinate tetrahedral PO4 to five coordinate tbp OndashMF3ndashO and six

1enspThe description of the trigonal planar monoanionic PO3 species as a phosphoryl group is in line with long-established usage in biochemistry biomolecular chemistry and molecular biology We note that the IUPAC recommendation is that the species lsquophosphoryl grouprsquo relates to the neutral diatomic trivalent species equivPO2enspBeF3

thinspminus PDB ligand name Beryllium trifluoride ion PDB code BEF IUPAC name Trifluoridoberyllate3enspAlF4

thinspminus PDB ligand code ALF IUPAC name Tetrafluoridoaluminate4enspAlF3 PDB and IUPAC name Aluminum fluoride PDB ligand code AF35enspMgF3

thinspminus PDB ligand code MGF IUPAC name Trifluoridomagnesate















140BeF3

ndash

AIF4ndash

MgF3ndash

MgF32 ndash

VO43 ndash

WO42 ndash

AIF30

120

100

80

60

40

20

0

1994

ndash199

6

1994

ndash199

9

1994

ndash200

2

1994

ndash200

5

1994

ndash200

8

1994

ndash201

1

1994

ndash201

4

1994

ndash201

7















Fig A1aensp

Fig A1bensp









Fig A1censp

O

HO

ThyO

PO

PO

PO

PO

O O O OO O OO

PA PG

OAde

HO OH PB PD

Fig A1densp

Fig A1eensp

Fig A1f1ensp

Fig A1f2ensp













O

OH

GuaO

PO

PO

PO

O O OO O O

PB5

5prime

PG5 PA5

O PO P

O

OOO

O

PB3 PA3

3prime

Fig A3aensp

OPO3

OPO3

OPO3

OO3PO

O3PO

PO

PO

O OOO

PA5 PB5

PA1

PA2

PA3

PA4

PA6

Fig A3bensp














Fig B1bensp

Fig B1densp












O

HO OH

GuaO

PO

PO

PO

O O SO O O5prime

O3A

S1A O2A

Fig B1eensp

O

HO OH

AdeO

PCH2

PO

PO

O O OO O O

5prime

O1AO2A

C3A

PA

Fig B1gensp

O

HO OH

AdeO

PO

PCH2O

O OO O

PO

O O

O3BC4B

Fig B1fensp










O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA


HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp











Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp









































140BeF3

ndash

AIF4ndash

MgF3ndash

MgF32 ndash

VO43 ndash

WO42 ndash

AIF30

120

100

80

60

40

20

0

1994

ndash199

6

1994

ndash199

9

1994

ndash200

2

1994

ndash200

5

1994

ndash200

8

1994

ndash201

1

1994

ndash201

4

1994

ndash201

7















Fig A1aensp

Fig A1bensp









Fig A1censp

O

HO

ThyO

PO

PO

PO

PO

O O O OO O OO

PA PG

OAde

HO OH PB PD

Fig A1densp

Fig A1eensp

Fig A1f1ensp

Fig A1f2ensp













O

OH

GuaO

PO

PO

PO

O O OO O O

PB5

5prime

PG5 PA5

O PO P

O

OOO

O

PB3 PA3

3prime

Fig A3aensp

OPO3

OPO3

OPO3

OO3PO

O3PO

PO

PO

O OOO

PA5 PB5

PA1

PA2

PA3

PA4

PA6

Fig A3bensp














Fig B1bensp

Fig B1densp












O

HO OH

GuaO

PO

PO

PO

O O SO O O5prime

O3A

S1A O2A

Fig B1eensp

O

HO OH

AdeO

PCH2

PO

PO

O O OO O O

5prime

O1AO2A

C3A

PA

Fig B1gensp

O

HO OH

AdeO

PO

PCH2O

O OO O

PO

O O

O3BC4B

Fig B1fensp










O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA


HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp











Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp








































Fig A1aensp

Fig A1bensp









Fig A1censp

O

HO

ThyO

PO

PO

PO

PO

O O O OO O OO

PA PG

OAde

HO OH PB PD

Fig A1densp

Fig A1eensp

Fig A1f1ensp

Fig A1f2ensp













O

OH

GuaO

PO

PO

PO

O O OO O O

PB5

5prime

PG5 PA5

O PO P

O

OOO

O

PB3 PA3

3prime

Fig A3aensp

OPO3

OPO3

OPO3

OO3PO

O3PO

PO

PO

O OOO

PA5 PB5

PA1

PA2

PA3

PA4

PA6

Fig A3bensp














Fig B1bensp

Fig B1densp












O

HO OH

GuaO

PO

PO

PO

O O SO O O5prime

O3A

S1A O2A

Fig B1eensp

O

HO OH

AdeO

PCH2

PO

PO

O O OO O O

5prime

O1AO2A

C3A

PA

Fig B1gensp

O

HO OH

AdeO

PO

PCH2O

O OO O

PO

O O

O3BC4B

Fig B1fensp










O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA


HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp











Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp


































Fig A1censp

O

HO

ThyO

PO

PO

PO

PO

O O O OO O OO

PA PG

OAde

HO OH PB PD

Fig A1densp

Fig A1eensp

Fig A1f1ensp

Fig A1f2ensp













O

OH

GuaO

PO

PO

PO

O O OO O O

PB5

5prime

PG5 PA5

O PO P

O

OOO

O

PB3 PA3

3prime

Fig A3aensp

OPO3

OPO3

OPO3

OO3PO

O3PO

PO

PO

O OOO

PA5 PB5

PA1

PA2

PA3

PA4

PA6

Fig A3bensp














Fig B1bensp

Fig B1densp












O

HO OH

GuaO

PO

PO

PO

O O SO O O5prime

O3A

S1A O2A

Fig B1eensp

O

HO OH

AdeO

PCH2

PO

PO

O O OO O O

5prime

O1AO2A

C3A

PA

Fig B1gensp

O

HO OH

AdeO

PO

PCH2O

O OO O

PO

O O

O3BC4B

Fig B1fensp










O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA


HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp











Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp






































O

OH

GuaO

PO

PO

PO

O O OO O O

PB5

5prime

PG5 PA5

O PO P

O

OOO

O

PB3 PA3

3prime

Fig A3aensp

OPO3

OPO3

OPO3

OO3PO

O3PO

PO

PO

O OOO

PA5 PB5

PA1

PA2

PA3

PA4

PA6

Fig A3bensp














Fig B1bensp

Fig B1densp












O

HO OH

GuaO

PO

PO

PO

O O SO O O5prime

O3A

S1A O2A

Fig B1eensp

O

HO OH

AdeO

PCH2

PO

PO

O O OO O O

5prime

O1AO2A

C3A

PA

Fig B1gensp

O

HO OH

AdeO

PO

PCH2O

O OO O

PO

O O

O3BC4B

Fig B1fensp










O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA


HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp











Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp







































Fig B1bensp

Fig B1densp












O

HO OH

GuaO

PO

PO

PO

O O SO O O5prime

O3A

S1A O2A

Fig B1eensp

O

HO OH

AdeO

PCH2

PO

PO

O O OO O O

5prime

O1AO2A

C3A

PA

Fig B1gensp

O

HO OH

AdeO

PO

PCH2O

O OO O

PO

O O

O3BC4B

Fig B1fensp










O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA


HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp











Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp





































O

HO OH

GuaO

PO

PO

PO

O O SO O O5prime

O3A

S1A O2A

Fig B1eensp

O

HO OH

AdeO

PCH2

PO

PO

O O OO O O

5prime

O1AO2A

C3A

PA

Fig B1gensp

O

HO OH

AdeO

PO

PCH2O

O OO O

PO

O O

O3BC4B

Fig B1fensp










O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA


HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp











Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp



































O3A5

O3A3

O

OH

GuaO

PO

PO

O OO O5prime

O P

O PO

O

OO

O

3prime

PA5

PA3

PB5

PB3

Fig B2aensp

O

HO OH

NicotinamideO

PO

PO

O OO O

PA


HO OHPB

O1AO2A O1B O2B

O3A

Fig B2bensp

OPO3

OPO3

OPO3

O

O3PO

O3PO P

O P

O

O

OO

O

PA5

O2A5

O1A51

3 5

Fig B2censp

O

OH

GuaO

PO

PO

O OO O5prime

OP

OP

O

OOO O

3prime

O1A5 O2A5

O1A3O2A3

PA5

PA3

Fig B2densp











Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp





































Fig B3aensp

O

HO

GuaO

PO

PO

PS

O O OO O O

OH

O2GO3G

PG

PAPBS1G

Fig B4aensp








Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp


































Fig B4bensp

O

PO

OOHO

O

OH

NH2NArg100

NH2

HNH

N Arg116

NH2

H

H

HN

HNArg117

NHH

H

NH

HO

Asn190

O1A

O2A

O3A

O3

Fig B4c1ensp


O

P O

OOTyrosine

O

N

Ala474

H

NH

N

NH2

H

H

N

NH

H

N

HO

O1A

O2A

O3A

Arg478

O

O

Ile476

Gly477

O4

Fig B4c2ensp













O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp







































O

PO

OO

NH

HN

Arg268

H2N

NH2

H

O2A2

O3A2

O1A2

O2

O

OP

Ade

H

Lys262

N Val264

H

O

Thr265

OH

OH

OP

O

O O O OO5

PA5PB5

PA2

HO

Ser263

Fig B5aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2

O1

O4O3

Fig B6aensp

O

PO O

O

OHSer30

NH3Lys34

Leu80

HN

Gly79

O

O2P

O1P

O4P

O3P

Fig B6bensp












Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp






































Fig C1aensp


AdoO

PO

PO

BeO

PO

PO

Urd

FFO O O O O O O O

PA PB BeG PD PE


F1BeF2Be

O3B

Fig C1bensp










5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp




































5prime

Fig C2aensp

Fig C2bensp













Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp





































Fig C3aensp

Fig C3bensp







61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp
































61 C4 Vanadates




Fig C3censp

OVO

OO

O

O2V

Thr90

Me

Zn ZnO1V

O3V

O4V

Fig C4aensp









Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp


































Fig C4bensp

Fig C4censp

Fig C4densp




62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp






























62 C5 Tungstates







Fig C5aensp

Fig C5bensp








Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp

































Fig C5censp

Fig C5densp









Fig X1ensp

Fig X2ensp








Fig X3ensp


































Fig X1ensp

Fig X2ensp








Fig X3ensp

































Fig X3ensp





























g. michael blackburn*, jacqueline cherfils, gerard p. moss ... · chemistry, biophysics, chemistry,...

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